This paper introduces an open-source HEVC video call application called Kvazzup. This academic proposal is the first HEVC-based end-to-end video call system with a user-friendly Graphical User Interface for call management. Kvazzup is built on the Qt framework and it makes use of four open-source tools: Kvazaar for HEVC encoding, OpenHEVC for HEVC decoding, Opus codec for audio coding, and Live555 for managing RTP/RTCP traffic. In our experiments, Kvazzup is prototyped with low-complexity VGA and high-quality 720p video calls between two desktops. On an Intel 4-core i5 processor, the VGA call accounts for 17% of the total CPU time. Averagely, it requires a bit rate of 0.31 Mbit/s out of which 0.26 Mbit/s is taken by video and 0.05 Mbit/s by audio. In the 720p call, the respective figures are 46%, 1.13 Mbit/s, 1.08 Mbit/s, and 0.05 Mbit/s. These test cases also validate the feasibility of HEVC in different types of video calls. HEVC coding is shown to account for around 34% of the Kvazzup processing time in the VGA call and 45% in the 720p call.